Ch.12 Warm up 1. Define: genome, gametes, chromatin, chromosome, centromere, kinetochore, checkpoint, Cdk, MPF 2. What is the longest part of the cell.

Ch.12 Warm up 1. Define: genome, gametes, chromatin,

chromosome, centromere, kinetochore, checkpoint, Cdk, MPF

2. What is the longest part of the cell cycle? Why?

1. If the diploid number is 46, the haploid number is?

Ch. 12 Warm up 1. At the end of mitosis and cytokinesis, how

do daughter cells compare with their parent cell when it was in G1?

2. A cell’s DNA was measured at 5 picograms. DNA levels range from 3-6 pgms in the cell cycle . What stage of the cell cycle is this cell in. How do you know?

3. At metaphase, if the haploid number is 3, how many chromatids does this cell have?

Ch. 12 Warm upWhat is the correct phase of the cell cycle/mitosis for the following:A.Most cells that no longer divide or rarely divide are in this phaseB.Sister chromatids separate and move apartC.Mitotic spindle begins to formD.Cell plate or cleavage furrow formE.Chromosomes replicateF.Chromosomes line up on equatorial plateG.Nuclear membrane formsH.Chromosomes become visible

Ch. 12 Warm up 1. Describe the difference between plant

and animal cell division.2. Measurements of the DNA amount per

nucleus were taken. DNA levels ranged from 3-6 picograms per nucleus, what stage of the cell cycle are these cells in?a) One nucleus has 3 pgrmsb) One with 6 pgrmsc) 5 pgrms

3. Describe binary fission.

Ch. 12 Warm up1. How do we know the cell uses chemical

signals?

2. Summarize the cell control system.

3. Compare a cancer cell to a normal cell. What goes wrong?

Chapter 12: The Cell Cycle

What you must know: The structure of the duplicated

chromosome. The cell cycle and stages of mitosis. The role of kinases and cyclin in the

regulation of the cell cycle.

Cell Cycle: life of a cell from its formation until it divides

Functions of Cell Functions of Cell DivisionDivision: Reproduction, Growth and Tissue Repair

Cell Division

Process by which cell produces more of their kind Prokaryotes- binary fission Eukaryotes- mitosis and meiosis

Genome = all of a cell’s genetic info (DNA)

ProkaryoteProkaryote: single, circular chromosome EukaryoteEukaryote: more than one linear

chromosomesEg. Human:46 chromosomes, mouse:

40, fruit fly: 8

Chromatin Raw material that gives rise to chromosomes Long and thin during interphase Condenses and becomes visible under

microscope in mitosis

Each chromosome must be duplicated before cell division

Duplicated chromosome = 2 sister sister chromatids chromatids attached by a centromerecentromere

Categories of Cells

Somatic Cells Gametes

Body cells Diploid (2n): 2 of

each type of chromosome

Divide by mitosis Humans: 2n = 46

Sex cells (sperm/egg) Haploid (n): 1 of each

type of chromosome Divide by meiosis Humans: n = 23

Phases of the Cell Cycle

Phases of the Cell Cycle The mitotic phase alternates with interphase:

G1 S G2 mitosis cytokinesis Interphase (90% of cell cycle)G1 Phase: cell grows and carries out normal functions

S Phase: duplicates chromosomesG2 Phase: prepares for cell division

M Phase (mitotic)Mitosis: nucleus divides resulting in identical complete copies of chromosomes packaged into two new nucleiCytokinesis: cytoplasm divides resulting in two daughter cells

Mitosis Continuous process with observable structural

features: Chromosomes become visible (prophase) Alignment at the equator (metaphase) Separation of sister chromatids (anaphase) Form two daughter cells (telophase &

cytokinesis)

Phases of Mitosis

Mitosis: (PMAT) Prophase Metaphase Anaphase Telophase

Prophase & Prometaphase (Prepare)

• Nucleus and Nucleolus disappear

• Chromosomes appear as connected sister chromatids

• Mitotic spindle (made of microtubles) begins to form

• Centrosomes (pair centrioles) move to opposite ends of cell (plant cells do not have centrioles)

Metaphase & Anaphase(Middle) (Apart)

• Sister chromatids line up along the middle of the cell

• Ready to split

• Sister chromatids split move on microtubles to opposite poles in cell

• Spindle apparatus pulls sister chromatids to opposite poles

Telophase (Two new nuclei) & Cytokinesis Telophase Nuclei of newly split cells form Nucleoli appear Chromatin uncoils

Cytokinesis Cytoplasm of cell divided Animal Cells: cleavage furrow Plant Cells: cell plate forms

Cytokinesis in animal vs. plant cells

Results of Mitosis• Mitosis produces 2 daughter cells• The two daughter cells contain the exact same

number of chromosomes as the original parent cell• Daughter cells are DIPLOID

Animal Cell Division

Plant Cell Division

Which phases of the cell cycle can you identify?

The Mitotic Spindle: A Closer Look The mitotic spindle is an apparatus of microtubules

that controls chromosome movement during mitosis Assembly of spindle microtubules begins in the

centrosome, the microtubule organizing center The centrosome replicates, forming two

centrosomes that migrate to opposite ends of the cell, as spindle microtubules grow out from them

• The spindle includes the centrosomes, the spindle microtubules, and the asters (a radial array of short microtubules)

• Some spindle microtubules attach to the kinetochores of chromosomes and move the chromosomes to the metaphase plate

During anaphase

Chromosomes walked to poles by motor proteins

Kinetochore microtubules shorten at ends as they depolymerize

Nonkinetochore microtubules from opposite poles overlap and push against each other, elongating the cell

Prokaryote (Bacteria & Archaea) Division

Simple single-celled organism without nucleus

Genetic material single circular chromosome of DNA, anchored

to cell membrane Duplicated before division

Bacterial cells divide by Binary FissionBinary Fission

The Evolution of Mitosis

Since prokaryotes evolved before eukaryotes, mitosis probably evolved from binary fission

Certain protists exhibit types of cell division that seem intermediate between binary fission and mitosis

Bacterialchromosome

Chromosomes

Microtubules

Prokaryotes

Dinoflagellates

Intact nuclearenvelope

Kinetochoremicrotubules

Kinetochoremicrotubules

Intact nuclearenvelope

Diatoms

Centrosome

Most eukaryotes

Fragments ofnuclear envelope

Cell Cycle Control System Checkpoint = control point where

stop/go signals regulate the cell cycle

Major Checkpoints1.1. GG11 checkpoint checkpoint (Most important!)

Controlled by cell size, growth factors, environment “Go” completes whole cell cycle “Stop” cell enters nondividing state (G0 Phase)

Nerve, muscle cells stay at G0; liver cells called back from G0

2.2. GG22 checkpoint checkpoint Controlled by DNA replication completion, DNA Controlled by DNA replication completion, DNA

mutations, cell sizemutations, cell size

3.3. M-spindle (Metaphase) checkpointM-spindle (Metaphase) checkpoint Check spindle fiber (microtubule) attachment to

chromosomes at kinetochores (anchor sites)

GG11 Checkpoint Checkpoint

M-spindle Checkpoint:Mitotic spindle at metaphase

Kinetochore = proteins associated with DNA at centromere

Kinetochore = proteins associated with DNA at centromere

Internal Regulatory Molecules

• Kinases (cyclin-dependent kinase, Cdk): protein enzyme controls cell cycle; active when connected to cyclin

• Cyclins: proteins which attach to kinases to activate them; levels fluctuate in the cell cycle

Internal Regulatory Molecules

MPF = maturation-promoting factor• specific cyclin-Cdk complex which allows cells

to pass G2 and go to M phase

Growth Factor: proteins released by other cells to stimulate cell division

Example: For example, platelet-derived growth factor (PDGF) stimulates the division of human fibroblast cells in culture

Density-Dependent Inhibition: crowded cells normally stop dividing; cell-surface protein binds to adjoining cell to inhibit growth

Anchorage Dependence: cells must be attached to another cell or ECM to divide

External Regulatory Factors

External Regulatory FactorsPlatelet-derived growth factor (PDGF)

Cancer CellsCancer: disorder in which cells lose the ability to

control growth by not responding to regulation. multistep process of about 5-7 genetic changes

(for a human) for a cell to transform loses anchorage dependency and density-

dependency regulation Cancer Cells

Lack differentiation Have abnormal nuclei Form tumors Undergo metastasis

Normal Cells

Cancer Cells

Tumors = mass of abnormal cells Benign tumor: lump of cells remain at

original site Malignant tumor: invasive - impairs

functions of 1+ organs (called cancer) Metastasis: cells separate from tumor and

travel to other parts of body

Cancer Prevention

Anyone can get cancer but there are ways to minimize risk:

Don’t smoke, legal or illegal (includes hookahs, chew, 2nd-hand smoke)

Use sun protection Exercise and keep weight at ideal level Eat 5-7 servings of fruit and veggies a day Use screening/preventative

measures-breast/testicle/mole checks Practice abstinence or use condoms Vaccines (eg. HPV)

1.Name the phases starting at the top.

1.Name the phase2. Identify X3. Identify Y

5. Name the phase

6. Name the phase

10.  In humans, each cell (except sex cells) has how many chromosomes? ______11.  After mitosis, how many daughter cells are produced?  _______12.  After mitosis (in a human cell), each daughter cell has how many chromosomes? _____13.  How many phases are in MITOSIS? ___________14.  Which phase of the cell cycle is the longest?  _________

15.  During which phase does cytokinesis begin?  __________